Poor voice quality and codec selection with pjsua_wince

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On Tue, Aug 5, 2008 at 12:37 PM, Tzury Bar Yochay <tzury.by at gmail.com>wrote:

> Hi,
>
> I am trying to make a (decent) VoIP call using the following setup:
> - Asterix PBX (latest version) running on Trixbox
> - pjsua (command line tool) on a Windows XP host PC
> - Cellphone (O2) running Windows Mobile 5 and pjsua_wince application
>

FYI PocketPJ is the new (and better) app sample for WM.


>
> - LAN is connected using a LinkSys WRT54L (PC connected with cable and
> phone connected with WiFi)
>
>
First thing first, which pjsip version are you using on both sides of the
call?


> I manage to make a phone between the O2 and the PC, however the quality is
> very poor, with echo and disruptions of the voice.
>

This probably is a known problem. We use echo suppressor on WM and it's
performance is quite poor. If anyone can suggest better alternatives then
that will be great.


> Also, I periodically (~1 sec interval) get "silence noises" when there is
> no talk.
>
>
I suppose that's the VAD and keep-alive in action. This is also a known
issue: http://trac.pjsip.org/repos/ticket/490


> dq dump from pjsua:
>  [CONFIRMED] To: "801" <sip:801 at 10.0.0.151 <sip%3A801 at 10.0.0.151>
> >;tag=as18eb6d76
>    Call time: 00h:01m:12s, 1st res in 0 ms, conn in 0ms
>    SRTP status: Not active Crypto-suite: (null)
>    #0 PCMU @8KHz, sendrecv, peer=10.0.0.151:10406
>       RX pt=0, stat last update: 00h:00m:02.781s ago
>          total 3.5Kpkt 570.8KB (713.6KB +IP hdr) @avg=63.1Kbps/78.8Kbps
>          pkt loss=0 (0.0%), dup=0 (0.0%), reorder=0 (0.0%)
>                (msec)    min     avg     max     last    dev
>          loss period:   0.000   0.000   0.000   0.000   0.000
>          jitter     :   0.000   3.517  21.375   4.000   2.393
>       TX pt=0, ptime=20ms, stat last update: 00h:00m:02.375s ago
>          total 3.5Kpkt 575.4KB (719.3KB +IP hdr) @avg 63.6Kbps/79.5Kbps
>          pkt loss=0 (0.0%), dup=0 (0.0%), reorder=0 (0.0%)
>                (msec)    min     avg     max     last    dev
>          loss period:   0.000   0.000   0.000   0.000   0.000
>          jitter     :  18.875  21.696  24.375  22.375   1.661
>      RTT msec       :   2.014   5.922  11.016   5.020   2.840
>
>
> I have the following questions:
> 1. Why is the PCMU codec selected and not Speex (I have set Speex to be in
> the highest priority on both sides)? How can I make it choose something else
> other than PCMU?
> When I tries setting all Codecs priorities except Speex to zero, I couldn't
> establish a conversation.
>
>
Did you put/enable Speex in the build?


> 2. I set --no-vad in the pjsua console on the PC and set:
> #   define PJMEDIA_CODEC_MAX_SILENCE_PERIOD    -1
> before deploying the file to the mobile device.
> This should have disabled the 'silence noises' but it doesn't. Am I missing
> something?
>
>
Disabling the vad with --no-vad should be sufficient. Of course you'd need
to do the same in the WM side as well.



> 3. Although I use non-routable IPs, I have the entire system on a LAN. Why
> does it think I'm behind a NAT and tunnels everything through the Asterix?
> Is there a way to tell the software to contact directly?
> I've set the following in pjsua_wince.cpp:
>     // Use this to disable STUN
> #   define STUN_DOMAIN    NULL
> #   define STUN_SERVER    NULL
> And it does not seem to have any effect.
>
>
If you're calling an Asterisk number (or otherwise calling via Asterisk),
then it's up to your Asterisk configuration whether to tunnel the audio or
not, no?


> 4. Was anyone able to succesfully deploy such (or similar) enviorment? Can
> you provide some hints?
>
> 5. It seems that the changes I make have very little or no effect on the
> overall quality. For example, I set:
> #   define PJMEDIA_SOUND_BUFFER_COUNT        20
> and expected to have a very long delay, but it had no effect.
> Am I doing something wrong?
>
>
With the latest (0.9) pjsip, that setting has less effect now as the buffer
count will be calculated dynamically.

Cheers
 Benny
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